COMPREHENSIVE STUDY OF RADIOACTIVE BACKGROUND IN THE COASTAL WATERS OF SOUTH CHINA SEA AREA

This report summarizes the radioactive background measured in the coastal waters of South China Sea for three recent years. The sea area is located at 110°—117°E and 20°—24°N. The items included sea water, marine organisms and sediments. The radioactive materials for detection included: gross U, gross β,~(238)U,~(232)Th, ~(226)Ra,~(40)K, ~(90)Sr,~(137)Cs, ~3H, etc. The contents of radioactive materials in sea water are: gross U, (25.6—40.9)×10~(-3) Bq/1; ~(90)Sr, (2.5—4.7)×10~(-3) Bq/1; ~(137)Cs, (2.0—4.4)×10~(-3) Bq/1; gross β, (55.5—87.5)×10~(-3) Bq/1 and ~3H, 0.33-0.82 Bq/1. The contents of radioactive materials in the sediments are ~(238)U, 51.2—99.7 Bq/kg(dry); ~(232)Th, 38.1—62.1 Bq/kg(dry); ~(226)Ra, 24.3—59.1 Bq/kg(dry); ~(137)Cs, 1.5—2.4 Bq/kg(dry); ~(40)K, 416.3—876. 1 Bq/kg(dry) and gross β, 569.2—912.2 Bq/kg(dry). The contents of radioactive mateials in the marine organism are ~(238)U, 21.0—99.2 Bq/kg(dry); ~(232)Th, 30.4—111.5 Bq/kg (dry); ~(226)Ra, 7.1—34.7 Bq/kg(dry); ~(40)K, 1069.2—2132.7 Bq/kg(dry); gross β, 1020.0—2492. 0 Bq/kg(dry). The radioactive contents in fishes are: ~(238)U, 4.2—12.0 Bq/kg(dry); ~(232)Th, 4.7—57.9 Bq/kg(dry); ~(226)Ra, 1.3—7.1 Bq/kg (dry); ~(137)Cs, 0.4—0.9 Bq/kg(dry).